A conventional fuel cell comprises at least one anode/cathode electrochemical couple separated by an ionic conductor, with fuel and oxidant streams fed separately and respectively to the anode and the cathode via dedicated flow fields that are in electronic contact with each electrode. In the conventional jargon the term “fuel cell” is used for both a single anode/cathode couple (also called a “cell” or more specifically a “unit cell”) and to a multi-cell stack that is usually configured to operate in a bipolar mode, with the individual unit cells electronically connected in series. Monopolar operation of a multi-cell stack, with individual unit cells electronically connected in parallel, is known but not normally practiced.
In a conventional bipolar fuel cell stack, fuel and oxidant streams are fed separately (dual feed) into the fuel cell via flow fields in bipolar plates that physically isolate the fuel and oxidant streams. In polymer electrolyte membrane (PEM) type fuel cells, a polymer electrolyte membrane separator is located in the fuel cell between the anode and cathode to permit ionic transport between the anode and cathode, while preventing electronic communication through the membrane between the electrodes and limiting or preventing so-called crossover of the fuel and/or oxidant from one anodic or cathodic compartment of the fuel cell to the other anodic or cathodic compartment. The separate feeds and bipolar plates add complexity, cost and size to the fuel cells and auxiliary equipment (i.e. the so-called “balance of plant” that supports the fuel cell operation), which serves as a limitation on cost/performance metrics in conventional fuel cells.